Quote:
Originally Posted by vugtitan
solar cells have high output impedance depending on light falling on the cells.the 8 volts figure is only true if no current is being drawn.as current is being drawn into the 3.7 volts lithium battery the output voltage will fall to just over 3.7 volt.
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Even with the output voltage sagging due to load, it isn't going to be 3.7V. The possibility of overcharging the battery still exists though.
If you really want to build a solar charger for the Kindle then create an array with a LDO regulator so you can wire it into the USB socket. Being cheap and using a diode or two to drop the voltage could work as well but regulation will be poor. Whether it is worthwhile making this yourself becomes slightly debatable at this point because there are many cheap USB solar charger gadgets around which may prove to be better value.
Either way, all the best to your project. I'm just concerned about the safety of yourself and the Kindle.